How about Watership Down? The novel is one of my all-time favourites, and moved me to tears the first time I read it (I was nine). But I also learned some profound lessons from that book, about the price of freedom, and the importance of standing against tyranny. It's safe to say I wasn't the same person after reading it. A remarkable book.

The 1978 film isn't bad either. It's a decent enough adaptation, covering the main events of the book. :)